The boat will be wonderful! We have chartered the 393PC and the 474PC many times. We are leaving in 3 days for a charter on 393PCX (maybe Boatboy's!) I will let you know upon our return how much the larger engines help but I imagine for the low cost to upgrade it will be well work it! I found the 393PC a little underpowered. With that said, don't push it. As stated above, run at a lower RPM to save fuel and make your ride so much more enjoyable. Also, the 393PC has a history of overheating if it is run hard. Take your time.....certainly no rush.
As for space, you will have plenty. The lead on the starboard side is perfect! Just watch out....your guests will want to come over and use your shower!
Handling......also quite good. It has relatively small rudders so your rudder control is not great. However, the props are so far apart you can make the boat do just about anything you want.
Overall, the boat is perfect for a charter. You will not be disappointed!